There is a lot that goes into an assessment for violence towards self or others. First, it is 
imperative to gather as much behavioral and situational information as possible. We don’t always have time to gather background data if the situation becomes more immediate. The more control the person wants to have and the less impulse control they maintain makes a threat assessment more immediate.
When we do have time (most times we do) we need to gather intel such as criminal court records. It is important to look at whether the conviction was a felony or misdemeanor, but remember the initial charge may have been pled down to a lesser charge which in my opinion is done too often.
We can’t just look at the charge, but rather use it as a starting point for us to look deeper into the mind of the subject to assess his/her level of violence.
Don’t forget to research Civil Court Records as well. Is there a restraining order on file and what created the need for the RO? Was it due to a domestic violence issue or a corporate restraining order for past threats against an organization?
We are looking for as much behavioral intel as possible. Example: Divorce Records. It may be possible to gather what his/her behavior was like during the divorce. Aggressive, passive or physically abusive.
In regards to my first post, if the employer asked the right questions during the pre-employment interview, it might have deterred hiring a high threat employee. Example: How did you deal with conflict with your last employer? Please provide an example.